Glossarytaught in EX7.01, M3.08
Assumption cell
Also called input cell, driver cell.
A labelled cell holding a single input, referenced everywhere it is needed and changed in one place.
Gathering the assumptions onto one sheet turns a model into an instrument. Sensitivity tables become possible and scenarios become a matter of switching a column. Reviewers can also see the whole set of judgements in one view.
Keeping assumptions in cells also exposes how many a model actually contains, which is usually more than its author thinks.
If it can be argued about, it belongs in a cell.